If you fly Southwest, you are in the older more run down terminal... one day I will make a connection and fly way out of my way to take an airline that flies into their newer terminal. I digress...
Decent airport, easy to navigate. Plenty of services (food, shopping, gambling) when you get through security.
My only gripe is that no matter when I have flown out of McCarran, (different days, different times) the Southwest checkin area is a mob scene... chaos and long lines with tons of cranky people. It has been this way for years and I just don't get it considering they have had plenty of time to get it together. You have to show up with no less than 120-90 minutes leeway to departure to ensure you don't leave it to chance and miss your flight.